Snap fasteners of varied types are known in the art, and the present invention is concerned with improvements in the so-called spring socket type. FIG. 1 illustrates a conventional snap fastener of this type, which comprises a spring socket 1, a stud 2 to snap in the socket, and pronged backing members 3, 4 for securing, respectively, the socket and the stud to opposed parts of a garment. The socket 1 has inwardly protruding split spring flaps 5, each of which terminates with a bead-like tongue 6 and can elastically engage with, and disengage from, an outwardly protruding bead 7 of the stud 2. The socket 1 and the stud 2 are formed, respectively, with inwardly curved guide rims 8,9. When attaching these members to a garment, the legs (prongs) 10 of the backing members are forced through opposed parts of the cloth until they are pressed against and bent at the tips against the guide rims 8,9.
The spring socket 1 and the stud 2, when thus attached to the garment and engaged together, are subject to tensions from the cloth that act on their sides (on the left and right as viewed in FIG. 1). For this reason the tongues 6 often become permanently deformed after long-time service.
When the stud 2 is fit in the socket and pulled horizontally the flaps 5 flex and contact the rear wall of the flaps. The flexing of the flaps 5 is still within the elastic deformation. When the horizontal pulling force exceeds a given level, the tongues 6 become permanently deformed. In actual use, this deformation will occur in various portions and, after a long period of use, will lead to loosening of the socket hole defined by the tongues 6. This deformation occurs because the back side of the tongues 6 directly engages the rim portion of the socket which is rigid and the stud 7 forces the tongues horizontally to and against the rim portion to cause deformation.
Moreover, the spring socket of the construction described has a mostly curved surface, leaving too little a flat surface to bear characters, trademark, symbol, or other insignia.